Ana, Bill,--and Claudette?

After one of the slowest starts to hurricane season in the past twenty years, the hurricane season of 2009 has exploded with activity over the past 48 hours. This morning, Tropical Depression Four joined Ana and Bill in the Atlantic, and appears poised to become Tropical Storm Claudette later today. Indeed, this may already be Claudette, as morning's QuickSCAT pass showed top winds of 45 mph. NEXRAD radar animations out of Tallahassee, FL, show a small but well-organized tropical cyclone with plenty of heavy thunderstorm activity, and improving low-level spiral banding. Satellite loops show an area of intense thunderstorms with cold cloud tops expanding near the storm's center.

Figure 1. Current long-range radar out of Tallahassee, FL.

It's pretty amazing (and a little unnerving) how quickly this storm sprang up. TD 4 developed literally overnight, and has the potential to be a strong tropical storm by the time it makes landfall tonight along the Florida Peninsula. TD 4 reminds me of 2007's Hurricane Humberto, which became a hurricane just 24 hours after first appearing as a tropical depression. I don't think TD 4 has time to reach hurricane strength, since wind shear as diagnosed by the SHIPS model was moderate, 10 - 15 knots, but it does have time to strengthen into a 50 - 60 mph tropical storm before landfall. Given that the storm is so small, storm surge flooding should not exceed 3 -5 feet, and will not be the major hazard from TD 4; inland flooding from heavy rain of 3 - 6 inches is likely to be the main threat from the storm.

Tropical Storm Ana continues to struggleTropical Storm Ana continues to struggle. Dry air continues to plague the storm, thanks to the large area of Saharan air the storm is embedded in. Ana's heavy thunderstorms are limited to just one small spot near the center. Wind shear appears to have lessened some, though, since yesterday. Thunderstorms were not able to form at all near the center yesterday, since strong wind shear tends to blow a storm's heavy thunderstorms to one side of the storm, exposing the low-level center to view. With heavy thunderstorms building near the center this morning, shear appears to be less of a problem for the storm. Top winds seen by this morning's QuikSCAT pass were about 35 mph. The outer rain showers from Ana should appear on radar out of Martinique today.

Shear is low (5 - 10 knots), and is forecast to remain low for the next two days. SSTs are warm, 28°C, and will warm further over the next two days. However, there is so much dry air around Ana that significant strengthening appears unlikely. Nearly all of the models predict Ana will dissipate sometime in the next three days, though the HWRF and GFDL predict that this will happen because Ana will move over the rugged terrain of Hispaniola. Ana is likely not strong enough to survive an encounter with the big island that the Dominican Republic and Haiti share. At this time, it does not appear that Ana will be moist enough to cause a major flooding disaster on Hispaniola.

Figure 2. Water vapor image from this morning showing the large area of dry, Saharan air surrounding Ana, and lying to the northwest of Tropical Storm Bill. Image credit: NOAA/SSD

Tropical Storm Bill gathers strengthTropical Storm Bill is gathering strength in the middle Atlantic Ocean, and appears poised to become a powerful Cape Verdes-type hurricane later this week. QuikSCAT data from this morning shows a large circulation with top winds of 35 - 40 mph. Water vapor imagery (Figure 2) shows that there is some dry air to the northwest of Bill, and this dry air is being drawn into Bill's center, slowing intensification. It will likely take another day before Bill can moisten the atmosphere enough to ward off the dry air, and allow more significant intensification.

Wind shear is low, 5 - 10 knots, and is forecast to be in the low to moderate range, 5 - 15 knots, for the next five days. Sea Surface Temperatures are about 27.5°C, and will remain in the 27.5 - 28°C range the next four days, then warm substantially as the storm nears the Lesser Antilles Islands. The combination of low wind shear and sufficiently warm SSTs should allow Bill to intensify steadily to hurricane strength by Wednesday.

The big news is that our most reliable computer model from last year--the ECMWF model--appears to have made the right call yesterday, forecasting that a major trough of low pressure would develop along the U.S. East Coast, turning Bill more to the north. All of the other models--with the notable exception of the UKMET model--have now jumped on the ECMWF bandwagon, forecasting that Bill will pass well north of the Lesser Antilles Islands. The UKMET has Bill hitting the islands, but is being discounted since it is an outlier. It currently appears that the trough approaching the U.S. East Coast will be strong enough to recurve Bill before it reaches the U.S., though it is too early to be confident of this. Several of the longer range models show Bill passing near Bermuda or Nova Scotia, Canada.

Quoting seminolesfan:But that doesn't make sense. Either it's closed or it isn't.

The CoC is closed on QuickSCAT. The CoC's convection is not closed on radar. Are you happy now? I figured if I said "the CoC is almost closed on radar" it would make sense to someone who even halfway understands meteorology. But you guys seem to want to argue semantics this afternoon.

2. A TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL LOW IS PRODUCINGDISORGANIZED CLOUDINESS AND SHOWERS FROM THE WESTERN CARIBBEAN SEANORTHWARD ACROSS CUBA AND THE BAHAMAS TO SOUTH FLORIDA. THISACTIVITY IS EXPECTED TO SPREAD WEST-NORTHWESTWARD OVER THESOUTHEASTERN GULF OF MEXICO DURING THE NEXT COUPLE OF DAYS.THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEMBECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

Ya know, what is weird about this is I saw on a model somewhere (may have been here) of some type of tropical developent forming around that general area and bringing to around the TX/LA border. Not saying that will happen, just making a note of it.

Strongly disagree. How could they give a disorganized mess anything higher than a low? Just because their are warm waters? It would have been silly. At the time convection was limited and disorganized.

100% agreed. This was a big fluke of a system. Maybe not a fluke, but certainly a huge surprise! I doubt anyone gave the pre-Humberto wave much credit before any development occurred either.

Its amazing how Claudette gets the amount of attention on this blog..here in Pcola its like a non event without even the little update box on the tv. About to pick a friend up at the airport..no flight delay or any mention on the airline's website. When something bad is about to happen in the way of a storm..its way different than this

Its a great time of year...West Virginia Mountaineer football...English Premier League soccer and now hurricane season...my trifecta!

Live in Houston ...survived Ike and I don't need anymore of the darn things coming this way....just bought a natural gas generator and having it installed on 8-26...no more going without power for 15 days for me.

Love to read the "experts" on here...just not sure who the most "expertest" is though!

(;~)

Some of our experts include people such as Drak, 456, StormW, WeatherStudent and Category5HitsNY

I grew up on the original Weather Channel - it was just like the original CNN. No nonsense. CNN had their half hour and they repeated it non-stop. Always counted on them to be live and have breaking news immediately. They too, went sensationalist, mainstream, SOLD OUT, whatever you want to call it.

Those two channels were amazing in their inception and then turned into trash as time went on. Not even worth watching.

I see what you're saying. I live in Miami and there have been times when thunderstorms were rolling in and I turned on TWC to get a report and Storm Stories was on.

Its a great time of year...West Virginia Mountaineer football...English Premier League soccer and now hurricane season...my trifecta!

Live in Houston ...survived Ike and I don't need anymore of the darn things coming this way....just bought a natural gas generator and having it installed on 8-26...no more going without power for 15 days for me.

Love to read the "experts" on here...just not sure who the most "expertest" is though!

that is strange...when i listened to lyons this morning b4 church, he said that claudette (not named at that point) looked as tho it was trying to wrap around itself...said he looked for it to be named but not necessarily a hurricane at landfall...said the most impact would be rain, but flooding would not be widespread, mainly would be the areas that usually flood with heavy rains...even put up the graph...everything low except rain...that was in the medium range on the graph

2. A TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL LOW IS PRODUCINGDISORGANIZED CLOUDINESS AND SHOWERS FROM THE WESTERN CARIBBEAN SEANORTHWARD ACROSS CUBA AND THE BAHAMAS TO SOUTH FLORIDA. THISACTIVITY IS EXPECTED TO SPREAD WEST-NORTHWESTWARD OVER THESOUTHEASTERN GULF OF MEXICO DURING THE NEXT COUPLE OF DAYS.THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEMBECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

$$FORECASTER BEVEN

LOL! Assuredly spoken without any reason whatsoever for making such a forecast.

Absolutely one of the biggest dishes of crow ever served should be served to not only Beven...but the entire NHC!

Hilarious!!!

Strongly disagree. How could they give a disorganized mess anything higher than low? Just because their are warm waters? It would have been silly. At the time convection was limited and disorganized.

Quoting hunkerdown:Doc Lyons also said earlier today, right before Claudette was named, that winds at the center were less than 25mph and he doubted whether it would strengthen into anything prior to landfall...

RI (rapid intensification) happened. Hard to predict, but someone should have predicted it based on teh water temperatires in the GOM

2. A TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL LOW IS PRODUCINGDISORGANIZED CLOUDINESS AND SHOWERS FROM THE WESTERN CARIBBEAN SEANORTHWARD ACROSS CUBA AND THE BAHAMAS TO SOUTH FLORIDA. THISACTIVITY IS EXPECTED TO SPREAD WEST-NORTHWESTWARD OVER THESOUTHEASTERN GULF OF MEXICO DURING THE NEXT COUPLE OF DAYS.THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEMBECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

$$FORECASTER BEVEN

LOL! Assuredly spoken without any reason whatsoever for making such a forecast.

Absolutely one of the biggest dishes of crow ever served should be served to not only Beven...but the entire NHC!

Hilarious!!!

Tropical Depression Four formed in the eastern Gulf of Mexico on August 16. The disturbance developed rapidly and formation was not expected until just a few hours before its declaration as a tropical depression. As recently as 9 hours before the storm's formation, the NHC gave the system a less than 30% chance of developing in the next 48 hours.[11] In an update statement issued at 12:15 p.m. EDT on August 16, 2009, Tropical Depression Four was upgraded to Tropical Storm Claudette based on a NOAA radar in Tallahassee.

What a crazy turn around of event in the past 24 hrs yesterday the story was Ana and Bill and all of the sudden Claudethe appears to stole the show BTW don't discard a CAT 1 forming in the next 12-18 before landfalling is Flarida panthandle.

Quoting hunkerdown:Doc Lyons also said earlier today, right before Claudette was named, that winds at the center were less than 25mph and he doubted whether it would strengthen into anything prior to landfall...

Well many buoys showed weak winds this morning. I could see where he was coming from.

Quoting MississippiWx:Center of Claudette starting to show itself again SSE of Panama City. Looks like she will come ashore a little west of PCB if trends continue. The slower she goes, the further west she goes as the ridge will continue to build westward with time.

agreed, looking better than early, early this morning, which is the last time it looked like an eyewall feature, I know it's not an eyewall, but looks like one. I'm sure this area contains some good, strong gusts!

Quoting GBguy88:Hey guys, is Ana moving more NNW or is it just NW? I'm in Pensacola, and trying to decide whether or not to drive East to try and intercept the center (just a tropical storm, but I need my fix...you know how it is). It looks to me like it may have enough westward motion to come in somewhere near Destin...any thoughts?

I have a thought. (This storm is Claudette, Ana is in the Atlantic.). Stay home and stay away from that area and off Hwy 98. The Destin Pass and other low lying areas to the east along Hwy 98 will likely washout or at least get covered with water at some point..